1. School of Energy and Power Engineering, Changsha University of Science and Technology, Changsha, Hunan, People's Republic of China
2. Research Center for Advanced Powertrain Technology, Hunan University, Changsha, People's Republic of China
3. College of Electric and Information Technology, Hunan University, Changsha, Hunan, People's Republic of China
4. School of Electrical and Information, Changsha University of Science and Technology, Changsha, Hunan, People's Republic of China
5. Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
6. College of Mathematics and Econometrics, Hunan University, Changsha, Hunan, People's Republic of China